The present invention is concerned with conveniently and rapidly initially engaging or contacting a well part at the sea floor from a floating vessel in relatively deep water. Prior proposed systems for making such contact have provided a guide post means on a sea floor well template and acoustic controlled means for bringing a guide line to the top end of the guide post and attaching the guide line thereto. In such prior proposed systems, a guide post was necessary on the sea floor well template.
Other prior proposed systems for initially contacting a sea floor template included lowering a pipe string from a floating vessel to engage a cooperable part on a sea floor template. The bottom end of the pipe string was laterally moved by lateral movement of the floating vessel. In deep water, it will be apparent that lateral displacement of the vessel and the relative lateral displacement of the pipe string end near the sea floor incorporated a substantial time lag. Accurate control of lateral displacement of the submerged pipe end by movement of the vessel was very difficult and time consuming.
When such a prior pipe string was coupled together with the pipe sections, as the lower end of the pipe string reached the vicinity of the well template, pressure fluid was introduced through the pipe string for discharge from nozzles at the lower end of the pipe string to laterally displace the end of the pipe string so that proper mating with a well template part could be accomplished. The use of such pressure fluid means in a pipe string was usually controlled by valve means at the floating vessel. In long pipe strings, it is obvious that displacement of the submerged pipe string end to a preselected position at the sea floor was difficult because of delayed response of the pipe string end to fluid pressure control at the floating vessel.
Such prior proposed systems which lowered a pipe string to a well template included disadvantages in that control of the bottom end of the pipe string was erratic and imprecise and was not predictably repeatable. Another disadvantage was that since the control valves for the fluid pressure were located at the vessel and not at the pipe string end and since the pipe string was often used as a conduit for the fluid pressure means, continuous control of the pipe end as it descended was not possible, and only became possible when the pipe end was adjacent the sea floor.
In deep water installations, it is desirable that the descending pipe string end be under control at all times. In a system for conducting well operations as described in copending application Ser. No. 889,112 owned by a common assignee, a plurality of riser pipe string may extend between the multiwell template and the floating vessel. It is desirable that the lower end of the descending pipe string remain clear of other objects in the vicinity to prevent entanglement therewith. Further, in some multiwell template means, precise control of the location of the bottom end of the riser pipe adjacent the template means is necessary to move the pipe string end into desired engagement with the template means while avoiding other objects in the immediate vicinity.